Hi Ben,
There are probably several ways of attacking the problem and there are probably those who can answer this question better than I can. But, I've got a suggestion that might help. The Panther turret is probably the easiest to enlarge because it's made-up of a series of flat planes that intersect at varous angles and having the 1/35 turret provides you with a working representation of a fullsize turret. Because the turret is made-up of flat segments you should be able to individually trace the outline of the individual planar segments on to a piece of paper. Once you've traced the segments, determine the percentage needed to enlarge the segments on a copier machine and once enlarged, transfer the enlarged segments from the paper onto some styrene sheet. It works well to use spray adhesive to join the paper to the plastic sheets then you can cut the enlarged segments out and the paper will peel off. Once you have the segements transferred and cut out of the plastic sheet, you can use the 1/35 turret to provide the proper angles for the construction of the larger turret. Although, you'll have to miter the sheets so the segments come together better. Once you've constructed the segements, this should give you a pretty accurate base to add all your detail to later. You might also want to get some original dimensional specs to check yourself during construction of the 1/9 scale turret to make sure the proportions are not straying away from the actuall size of the turret. The gun mantle and cupola might be tricky, but having the smaller turret will help you to get a sense of proportion.
That's my two cents! Good luck, I hope it works out.
Dave
